Trapped between drowning and desiccation: Riverine plants under hydropeaking

Area of Science:

• Ecology
• Environmental Science
• Botany

Background:

• Hydropower production causes hydropeaking, characterized by artificial flow fluctuations.
• These fluctuations create challenging growing conditions for riverine vegetation, impacting germination, survival, and growth.

Purpose of the Study:

• To identify plant species vulnerable or resistant to hydropeaking.
• To evaluate the impact of different hydropeaking scenarios on riparian plant species.

Main Methods:

• Assessed germination, survival, and physiological/morphological traits of 14 riparian plant species.
• Exposed species to controlled and real-life hydropeaking scenarios in field and greenhouse settings over three months.
• Measured plant physiological stress using 13C isotope discrimination.

Main Results:

• Half of the tested species exhibited poorer performance under hydropeaking (reduced germination, biomass, growth, and physiological stress).
• No specific hydropeaking scenario was consistently more damaging than others.
• Betula pubescens, Alnus incana, and Filipendula ulmifolia were highly vulnerable; Carex acuta showed resistance.
• Plants in perturbed scenarios accumulated more 13C, indicating physiological stress, especially under drought/flooding or high hydropeaking intensity.

Conclusions:

• All hydropeaking schemes can negatively impact riverine plant performance.
• Scenarios combining severe drought with frequent flooding pose a significant threat to riparian vegetation.
• Identifying hydropeaking-tolerant plant traits is crucial for understanding species' life cycle limits under altered flow regimes.